Natural gas which is a mixture of low molecular weight hydrocarbons and small amounts of higher hydrocarbons is contaminated with sulphur and nitrogen compounds as well as with oxides of carbon. Sulphur contaminants are hydrogen sulphide, carbonyl sulphide and mercaptans.
Process gas and fuel are produced by desulphurising sulphur containing natural gas streams. Harmful sulphur contaminants are removed by direct reduction of iron ore.
Conventional desulphurization methods include adsorption of the contaminants by metallic compounds, ceramic and metal oxides pellets, finely divided iron, and porous iron oxide. Direct reduction of iron ore also results in spongy iron having sulphur contaminant absorbing capability.
Molecular sieves and compounds such as Zinc oxide are generally used as decontaminants for hydrocarbon fuel gas. Cracking of components are to be avoided during such desulphurisation step.
Porous sponge iron derived from magnetite has also been used as a desulphurizing agent. Though found effective in many desulphurisation reactions, this spongy iron does not have very high adsorptive capacity.
An object of this invention is to develop a highly adsorbant porous sulpha sponge iron compound whose adsorbent capacity may be renewed or controlled to the desired level by repeated processing.
Yet another object of this invention is for a method of desulphurising natural gas by adsorbing sulphur containing contaminants in the above porous sulpha sponge iron compound. Desulphurization process according to this invention results in substantially freeing natural gas from such contaminants. Since this process is not carried out at high temperatures, cracking of natural gas is also avoided.